(1) Field of the Invention
The present invention relates to an operation instructing device for outputting an operation instruction to a portable information apparatus that includes the operation indication device.
(2) Description of the Related Art
In recent years, portable information apparatuses such as mobile phones have become increasingly reduced in size, and a screen display area of such portable information apparatuses has also become smaller. Accordingly, it becomes important to limit contents to be displayed in one screen. On the other hand, the portable information apparatuses are designed to be more and more multi-functional, and such a portable information apparatus has over 100 menu items. Therefore, the menu items are put in a complicated menu hierarchy, and a user has to repeat pressing buttons over and over to select a desired menu item.
In order to complement the tangled button operation, the Japanese Laid-Open Patent Application No. H6-4208, for example, discloses a technique for detecting a movement of a main body of an information processor corresponding to a user movement, and for switching and scaling up and down contents displayed in a screen based on a direction and quantity of the detected movement.
Further, the U.S. Pat. No.6,369,794, for example, discloses a technique for identifying user movements such as “swing” and “tap” for instructing operations such as switching contents displayed in a screen of a portable information apparatus.
Both of the above techniques detect a motion value of a portable information apparatus and changes the contents displayed in the screen according to the detected motion value. Correspondence between motion values and operations are set statically in advance.
However, the user movements differ greatly in individuals. A motion value of a movement made by a user who is not physically strong can be too small and judged to be an error, and a predetermined operation such as switching the contents in the display screen could fail. Similarly, when a motion value of a user movement is too strong, it can be judged to be an error caused by an accident such as dropping the portable information apparatus on the ground, and the predetermined operation such as switching the contents in the display screen could also fail.
The user movements also differ in movement types of an individual user, and side-to-side movements of one user can be stronger than back-and-forth movements of the same user.
In other words, such a case could happen, in which the contents displayed in the screen can switch when the portable information apparatus is moved side to side, but do not switch when the portable information apparatus is moved back and forth.